| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.5%
|
| -7 | Does not apply | 11 |
2.6%
|
| 0 | No obstacle | 97 |
22.6%
|
| 1 | Minor obstacle | 138 |
32.2%
|
| 2 | Moderate obstacle | 147 |
34.3%
|
| 3 | Major obstacle | 32 |
7.5%
|
| 4 | Very severe obstacle | 2 |
0.5%
|